1. Field of the Invention
The present invention relates to an improved apparatus for loading and unloading railroad cars, and more particularly to such an apparatus in which an articulating center support assembly is provided for added stability. An alternative embodiment of front and center support feet incorporate support rollers and a front bucket arm includes a retractable bucket stop block.
2. Description of the Related Art
Loading and unloading of open top railroad cars has traditionally been accomplished via large, fixed base cranes or similar systems stationed alongside a railroad depot. However, loading, or particularly unloading, must often be accomplished at a site remote from such a depot, such as during handling of cross-ties and track bed ballast for railroad construction or repair. Traditionally such unloading tasks have been accomplished via manual labor or by transporting large, highly specialized and expensive equipment to the job site. The disadvantages of manual labor are, of course, many, including lack of efficiency and added expense. On the other hand, the costs of purchasing or renting expensive specialized equipment and the costs of transporting the equipment to each job site can also be prohibitive.
U.S. Pat. No. 4,175,902 entitled APPARATUS FOR LOADING AND UNLOADING RAILROAD CARS (the '902 patent) and U.S. Pat. No. 4,190,394 entitled METHOD FOR LOADING AND UNLOADING RAILROAD CARS (the '394 patent) to Stanley Herzog et al. are directed to an apparatus and method, respectively, of employing a specially adapted backhoe-like machine which has the capability to load or unload open top railroad cars. In these patents, which are hereby incorporated herein by reference, the specially adapted backhoes, called "Cartoppers.TM.", can be easily transported to remote sites, where they are capable, with a trained operator and a front bucket mounted winch, of loading themselves onto the top of the railroad car. The machines can then be moved along the top of each railroad car as material, such as track ballast, railroad ties, coal, or other materials are unloaded from, or loaded onto the railroad car. The machines, when not employed in loading or unloading railroad cars, are versatile enough to be quickly converted for use in ordinary tasks such as digging, trenching, etc. which are unrelated to the loading or unloading tasks. However, a problem encountered with the original design, which had supports attached only to the front bucket and to the chassis behind the operator's cab, was the lack of stability when the machine was positioned atop a railroad car. Additionally, freedom of motion of the machines along the tops of railroad cars is restricted by the friction between the support feet, which in the '902 and '394 patents, are fixed skids, and the tops of the railroad car. In later versions of the loader/unloader, adaptability to uses other than loading or unloading was limited by a fixed front bucket stop block attached to the front bucket boom.
It is clear then, that the apparatus disclosed in the '902 and '394 patents needs to be modified to yield enhanced stability to the apparatus when it is positioned atop a railroad car. Any modifications should also preferably enhance, or at least not detract from the versatility of the machines for use in tasks unrelated to railroad car loading and unloading.